Electric arc stud welding apparatus

ABSTRACT

637,032. Electric welding. CYC-ARC, Ltd., and AINSWORTH, A. R. Nov. 24, 1947, Nos. 31058/47 and 5203/48. [Class 83 (iv)] In a portable arc stud-welder the studholder 25 is carried by a crosshead 21 from a piston 17 movable in a cylinder 3 and operated by a ram 44 through a liquid confined between the piston 17 and the ram 44. The holder 25 automatically adjusts the volume of confined liquid to suit the stud by drawing from or rejecting to a reservoir 5 through a port 35 shut on the first movement of the ram 44. The ram 44 is operated against a spring 46 by an electromagnetic solenoid core &amp;c. 45 to raise the holder 25 against a spring 56 for arcing. The speed of lift is controlled by a throttle valve 63 preset for stud diameter, material, &amp;c. The reservoir 5 has a variable volume portion 48 comprising a bellows and the liquid is totally enclosed. In a modification, Fig. 4 (not shown), the variable volume portion comprises a cylinder with a sprung piston. In a further modification, Fig. 7, the ram 185, piston 168 and bellows reservoir 175 are co-axial, the piston 168 remains stationary, and the stud holder 198 is carried by a cylinder 170 movable about the piston 168. The speed of lift during operation is controlled by presetting the spring 192 against which the solenoid core 184 operates. In a similar modification, Fig. 5 (not shown), the cylinder is stationary, the piston is movable and carries the stud holder on a crosshead and the reservoir comprises an annular chamber with a spring piston. In a further static form, Fig. 9, for use on a drill press or like machine having a vertically reciprocable tool carrier, solenoid core 203 drives the ram 206 through a pivoted lever, the piston 205 is parallel to the stud holder 213 and the fluid passages and reservoir 219 are combined in a single unit 204. In a final modification, Fig. 6 (not shown), the fluid passages are provided in a unit immersed in a fluid tank.

1949- A. R. AINSWORTH 2,479,092

ELECTRIC ARC STUD WELDING APPARATUS Filed April 12, 1948 5 Sheets-Sheet1 Aug. 16, 1949. A. R. AINSWORTH 2,479,092

ELECTRIC ARC STUD WELDING APPARATUS Filed April 12, 1948 5 Sheets-Sheet2 Aug. 16, 1949. A. R. AINSWORTH ELECTRIC ARC STUD WELDING APPARATUS 5Shets-Sheet 5 Filed April 12, 1948 g- 6, 1949- A. R. AINSWORTH 2,479,092

ELECTRIC ARC STUD WELDING APPARATUS Filed April 12, 1948 5 Sheets-Sheet4 1949- A. R. AINSWORTH 2,479,092

ELECTRIC ARC STUD WELDING APPARATUS Filed April 12, 1948 I 5Sheets-Sheet 5 Patented Aug. 16, 1949 ELECTRIC ARC STUD WELDINGAPPARATUS Arthur Ratclifie Ainsworth, London, England, as-

signor to Cyc-Arc Limited, London, England, a

British company Application April 12, 1948, Serial No. 20,426 In GreatBritain November 24, 1947 19 Claims.

This invention relates to electric arc stud welding apparatus, wherebymetal or alloy studs, tubes and the like may be Welded to metal or alloyplates, bodies and the like by a method in which the stud or the like(hereinafter termed the stud) and the plate or the like (hereinaftertermed the plate) are adapted to function as electrodes connected in thewelding circuit and between which electrodes the arc is struck, the studbeing first contacted with the plate and the weldin circuit being thenclosed, whereupon the stud is withdrawn through a short distance fromthe plate to strike the arc, the are being maintained for the periodrequired for the surfaces to be welded to acquire a satisfactory weldingtemperature, the stud being then pressed upon the plate to effect theweld, and the flow of current in the welding circuit being maintainedfor the period necessary for th completion of a satisfactory weld.

The invention has among its objects to provide an electric arc weldingapparatus that is self-adjusting to operate with studs of differinglengths within its capacity, to provide an apparatus in which themovement of the stud to strike the arc is effected through the medium ofa body of liquid contained within the apparatus and to provide anapparatus in which the rapidity of the movements of the stud may bereadily determined at the will of the operator.

According to the invention the apparatus is provided with a chuck orholder for the stud that is in fixed relation with a piston or plungerthat is movable in a cylinder or chamber into which may be forced aliquid that is subjected to the pressure of an operating ram, the liquidbeing confined between the piston or plunger and the ram and the latterbeing caused to become operative at the will of the operator.

The ram is advantageously caused to take up an inoperative position inwhich it opens communication between the cylinder or chamber and astorage chamber of variable capacity in which is confined a volume ofthe liquid which, if necessary, under a slight pressure, is caused tofollow any movement of the piston or plunger whereby the space availableto the liquid in the cylinder or chamber is increased, except when theram is operative to break the communication. Thus, when a stud ischarged into the chuck or holder of the apparatus and the apparatus isset in the operative position in relation to the plate to which the studis to be welded, the piston or plunger is automatically moved into theposition determined by the length of the stud, liquid flowing from thestorage chamber in the volume necessary to maintain the cylinder orchamber fully charged.

The invention is illustrated, by way of example, in the accompanyingdiagrammatic drawings representing several embodiments.

Figure 1 is a sectional elevation of a portable or hand tool accordingto the invention.

Figure 2 is a sectional elevation 0n the line 2-2 in Figure 1.

Figure 3 is a plan view of the tool represented in Figures 1 and 2, thecover plate being removed.

Figure 4 is a sectional elevation of a modified construction of portableor hand tool according to the invention, the cover plate and thesupports being omitted.

Figure 5 is a sectional elevation of a further modification inconstruction of the portable or hand tool according to the invention.

Figure 6 is a sectional elevation of a construction of apparatusaccording to the invention adapted for use upon a machine tool, such asa drilling machine.

In any embodiment of the invention it is preferred to include certainadvantageous features, with a view to securing a high degree ofefficiency in operation and ease of control.

The ram is advantageously actuated electromagnetically, for example, bythe transmission or application of the movement of the core of asolenoid to the ram. The control of the operation of the apparatus maybe effected electrically.

The return of the stud to the plate is advantageously effected by theaction of a spring that may be operative, for example, upon the chuck orholder or upon the piston or plunger.

Since the rapidity of the movements of the stud in relation to the platerequires to be controlled according to the diameter of the stud andrelated considerations, it is advantageous to provide for the control orregulation of the cross-sectional area of the passage or conduit bywhich the liquid flows to the cylinder or chamber from the space inwhich the ram operates. For the purpose, a needle or other like valvemay advantageously extend into a seating formed in the passage orconduit and may be provided under the control of a screw-threadedcontrol rod that may be fitted with an adjusting head adapted to beadjusted at the will of the operator, accordin to a scale of studdiameters that may be provided upon the head or upon an adjacent part ofthe body of the apparatus.

The storage chamber may be merely in the form of a cylinder with apiston mounted under the action of a spring exerting a light pressure.It is advantageous, however, to provide for the variation of capacity ofthe chamber by forming it either with a flexible diaphragm or of abellows construction.

In carrying the invention into effect, by way of example, in theapplication to a portable or hand tool as represented in Figures 1 to 3;of. the accompanying drawings, the body I of the tool is conveniently ablock of a metal, such as steel,

or a light alloy, such as aluminium silicon, substantially oval orelliptical in plan and having the upper and lower faces parallel, theupper face being deeply recessed, as at 2, to a depth approximating tohalf the depth of the body. On the major axis the bottom of the recessis pierced by three spaced cylindrical bores: 4, 5. The middle bore 3,which may extend to. the lower face of the body and there be plugged bya screwed plug 6, is adapted to serve as the cylinder to receive thepiston or plunger, while one-of the outer bores 4, intended to receivethe ram, may also extend to the lower face of the body and be plugged.The third bore 5, which may be of less depth, is required merely tofor-m a passage for communication with the storage chamber, ashereinafter described. The block is bored parallel with the upper andlower faces for the formation of two passages I and 8, the upper l ofwhich extends transversely through the ram bore 4 and the cylinder bore3 and ends where it meets the third bore 5, while the lower passage 8 isformed in a plane surface 9 recessed laterally in the end of the block Ibeneath the third bore and extends transversely through the cylinderbore 3 and ends in the ram bore 4. The passage 8 is of two diameters,the part ill of larger diameter extending from the outer end and endingin an annular coned face H after traversing the cylinder bore 3. Thepart H) of the passage is screw-threaded. The cylinder bore may beformed with a peripheral enlargement I 2 at the position at which theupper passage 1 traverses it.

The cylinder bore 3 is provided with a, liner l3 which may be of brass,bronze or other material, that is ofa length to extend short of thelower passage and to. project from the bore to an extent to form a headI l of. slightly increased diameter, that is screw-threaded to receive agland nut ladapted to confinea flexible packing ring it upon thehead'and about the piston or plunger H. The outer surface of the linermay be formed with-a peripheral channel I8 at the position. at which theupper transverse passage traverses it; The piston or plunger H isadvantageously of such length that when the lower end is at the level ofthe lower end of the liner [3 the upper end is clear of the gland nutl5. The lower part of the piston or plunger is formed with severalperipheral oil grooves is and the upper end is formed with an axial part26 of reduced diameter adapted to fit a bore in a transverse crosshead2|, the upwardly protuding part being screw-threaded toreceive a clamping nut 22. Thecrosshead is similarly. secured, in positions equallyspaced-from the piston, to two slide rods 23 that extend throughclearance holes bored through the body from. the bottom of the recess 2in the upper. face. Beneath the body the slide rods. aresimilarlysecured. to a transverse carrier 24.for.- the studchuck25. The

carrier 24 is bored for the passage of the up wardly directedscrewedstem 2,6- of: a metal disc 2'1, which stem passes through theeye; 28- of the supply cond t r and throu h a. bushlltoi in sulatingmaterial fitting the hole in the carrier and insulating discs 35, 3iabove and beneath the carrier and is clamped in position by a nut 32received upon the upwardly projecting end. The chuck 25 convenientlyscrews upon a short downwardly extending screwed stem 33 of the metaldisc 2'! so that it may be readily exchanged. It advantageously engagesthe studs by friction, being slotted for the purpose.

The ram bore 6 is similarly lined with a liner 34, of brass, bronze orother material, or of a magnetic material, that extends short of thelower transverse passage 8 and in the plane of the upper transversepassage I is formed with one or more transverse holes 35, affordingcommunication between the upper transverse passage and the interior ofthe liner. The liner may at this position be formed with a peripheralchannel 36, whereby liquid may flow around it and thus enter from morethan one position. The liner isadvantageously provided with a peripheralflange 31 which seats upon the bottom of the recess 2 in the body I, andis extended upwardly to form a means of location and centering for asolenoid 38, the coil 39 of which is enclosed in an outer cylinder andupper and lower rings 4| and d2 of magnetic material and a tubularlining 43 of non-magnetic material. The liner extends only partiallyinto the bore of the solenoid.

The ram 34 is provided as a plunger of nonmagnetic steel, slidablyfitting the bore of the liner 34, and having the upper part reduced incross-section and adapted to receive a solenoid core E5 or armature ofmagnetic material. The length of the ram advantageously is such that thelower end is positioned immediately above the transverse holes 35 in theliner 3 when the core 45 is in its uppermost and inoperative positionwith respect to the solenoid 38. The ram 44 is conveniently assisted totake up the inoperative position of the core by means of a helicalspring 55 surrounding it and positioned between the upper end of theliner and the lower face of the core. The ram is advantageously formedwith several peripheral oil grooves A l towards the lower end.

Co-axial with, or off-set from, the third bore, the bottom ofthe recess2 supports a cylindrical bellows 48 of rubber, rubber substitute orother flexible material unaffected by oil, which bellows is closed atthe upper end by a metal disc 39,0011- venientlyformed. with an axialfilling plug 50 for the charging of oil into the apparatus. The bellowsmay be secured in position by means of screws engaging lugs or a flangeat the bottom thereof, but is preferably provided at the lower end witha peripherally screw-threaded disc 5| that is received in ascrew-threaded seat 52 provided at the bottom of the recess 2.

The body is closed by a cover plate 53 of massive formation providedwith a saddle handle 54, or butt handle. The lower face of the coverplate is recessed, as at 55, for the reception of the solenoid 38, thecrosshead 2| and the bellows 48. The spring 56, serving to return thepiston or plunger in the downward direction, is conveniently positionedupon the crosshead 2! around the clamping nut 22 of the piston ll, thespring bearing at the upper end upon the bottom of the correspondingrecess in the cover plate.

The part It] ofv the lowertransverse passage 8 serves to receive asleeve 51 having the inner end coned to correspond with, the conedseatin H. in thepassage and having the outer part screwby rotation ofthe valve head 62, the adjustment.

of the coned end 53 in an axial opening 64 at the inner end of thesleeve 51. The latter is provided with one or more transverse holes 65that afford communication with the cylinder bore 3. The adjustedposition of the needle valve 60 may be determined by a lock nut 66 thatbears upon the head 59 of the sleeve.

The tool is adapted to be supported from the surface upon which studsare required to be welded by means of three similar supports eachconsisting of a sleeve 61, in which is slidably fitted a rod 68, theextension of the rods from the sleeves being determined by clampingscrews 59. It is convenient for one of the sleeves to be mounted inposition in, and to serve as the plug for, the lower end of the ram bore4.

While the bellows construction is advantageous for the formation of thestorage chamber, the latter may, as hereinbefore stated, bealternatively formed merely as a cylinder and piston. For this purpose,for example, the recess in the upper face of the block may be reduced inarea by the provision of a sufficiency of metal in the wall of therecess at the determined position to permit the boring therein of thecylinder to communicate with the third bore before referred to or totake the place of the said bore. The piston may be merely a metal cupcarrying a rubber or like cup and may be subjected to the pressure of ahelical spring, the upper end of which is received into a recess in thecover plate.

Figure 4 illustrates a construction of a portable or hand tool similarto, but modified from, the construction represented in Figures 1 to 3.The body 19 is not recessed in the upper face but the said face hasformed in it, along the major axis in spaced relation, three cylindricalborings H, l2, T3, of which 1| extends less than half the depth of thebody and has the central part continued as a sump 14, of a conical orother shape. The second and third borings l2 and 13 extend only so faras the lower transverse passage 15. The upper transverse passage 16connects the sump M with the borings l2 and 13 while the lower passage15 connects the lower ends of the said borings. The boring H is providedwith a liner 11 adapted to serve as the storage chamber, which extendsconsiderably above the upper face of the body to form a cylinder ofappreciable capacity, and at their lower ends the liners 11, i8 and 19,of the three borings are set upon annular shoulders or seatings at thelower ends of the borings with the interposition of a packing ring 89 ineach case. The lower ends of the liners may be engaged in screw-threadedparts of the borings, as illustrated with respect to the liners l8 and19. The upper end of the liner H is closed by a cap Bl which may bescrewed into position. The liner is fitted with a rubber or like piston82, with a piston cup 83 that is pressed downwardly by a helical spring84 of a wide range of resilience but of light strength.

The upper end of the liner 18 is flanged to seat upon the upper face ofthe body and the piston extended above the flange for connection to acrosshead rod 86 which, as in the first construction, is connected tothe stud chuck carrier 81 by rods 88. The spring 89 for returning thepiston 85 is disposed between the chuck carrier 81 and the lower face ofthe body 10. The arrangement of the liner 19, the ram 90, the solenoid9|, and solenoid core 92, closely resembles that of the firstconstruction. The needle valve 93 is directly. engaged, by screw-threadengagement, in the outer part 94 of the passage 15, and operatesdirectly in the cone seating 95. The tool may be provided with a coverplate and handle (not shown) and be supported from the surface uponwhich the stud is to be Welded by telescopic supports, as in the firstconstruction.

In the operation of such a tool, for example, the tool of Figures 1 to3, it will be understood that, within the range afforded by the limitsof the travel of the piston or plunger l'l, allowing for the smallmovement required for striking the arc, it is possible to charge thechuck 25 with studs of differing lengths and to apply the tool,

without any adjustment of the chuck, in position upon the plate to whichthe stud is to be welded, since the chuck will automatically take up acorresponding position with reference to the body of the tool. Thismovement is due to the fact that the spring 56, acting upon thecrosshead 2 l, tends always to move the chuck outwards in relation tothe body i, and therefore to cause the piston or plunger to move towardsthe inner limit of its travel, thus ejecting liquid into the bellows 48,through the transverse passages 8 and l, the ram 44 being then at theouter limit of its travel. Thus, according to the length of the studcarried by the chuck, the piston or plunger is pressed outwardly, and inconsequence draws the liquid from the storage chamber 48, through thetwo transverse passages and by way of the lower part of the ram bore.When the solenoid 39 is energised for the purpose of striking the arc,the ram 44 is moved forcibly downward in the liner 34, thus interruptingcommunication between the storage chamber and the lower part of theliner and driving the volume of liquid contained by the said partthrough the lower passage 8 at a rate determined by the adjustment ofthe needle valve 60, and thus into the piston cylinder, whereby thepiston I1 is moved outwardly to lift the chuck and strike the arc. Atthe end of the arc period, as determined by convenient timing apparatus(not shown), the solenoid is de-energised so that the spring 56, actingupon the piston or plunger, moves the latter downwardly for the returnof the stud to the plate, forcing the liquid beneath it, also at therate determined by the adjustment of the needle valve, into the lowertransverse passage and thus to the liner 34, pressing the ram 44upwardly, with the assistance of the spring 46 acting upon the solenoidcore, to the initial position and thus again opening communication withthe storage chamber.

The apparatus hereinbefore described are particularly adapted for use inconfined spaces or situations affording small head-room, but theinvention is, of course, not limited to such a design. Where the lengthof the apparatus is of no importance a design may be adopted in whichthe cylinder 96, the storage chamber 91, and the solenoid 98 areco-axially disposed, thus resulting in an apparatus that has similarityto a common form of pneumatic tool. Thus, the piston cylinder 96 may belowermost and may have the walls of the upper part diametricallyslotted, as at 99',

for the-reception of the cross-head I 00, and the slides or guides :I UImay pass through a belt I02, towards the lower endof the cylinder, whichbelt may also have mounted in it the supporting pins W3. A passage I04-for the admission of liquid beneath the piston I05 may be formed in thewall of the cylinder and the latter may be closed at the upper end by acap fitting I86, in which is formed the lower part of the ram chamberIll-l and arad'ial passage I08 controlled by the needle valve 109 andcommunicating with the passage I84 the wall of the cylinder. Suchfitting may also close the lower end of a hollow cylindrical fitting N0that is partitioned approximately midway and which the lower face of thepartition III is formed with a central cylindrical boss 112 that extendsinto contact with the upper face of the cap fitting I06 and has athrough bore adapted to receive the liner I I3 of the ram chamher, whichliner may extend into the cap fitting Hit; the annular space exterior tothe boss H2 serving as the storage chamber and housing an annular pistonH4 subjected to spring pressure or'alternatively an annular bellows.Communication between the storage chamber and the ram chamber may beafforded by a channel formed in the lower end face of the boss thatregisters with ports in the liner H3. The solenoid S8 is received-in theupper space'of the cylindrical fitting I I0, which may be closed by acover plate H5, fomn edwith a central space to receive the upper part ofthe solenoid core HE, when the latter is in the inoperative position,the cover plate being provided with a butt or D handle.

If it is preferred to avoid the use of a crosshead and slides or guidesin any of the foregoing designs of apparatus, a central extension of thepiston may project downwardly through a gland for connection directly tothe chuck carrier. This construction, however, is open to thedisadvantage that it is necessary to offset the lower passage and theneedle valve and to provide corresponding connecting passages.

In the design of a tool adapted for use upon a machine tool, such as adrilling machine, or for incorporation in a specially designed fixedbase apparatus, the body of the tool may comprise a simple tank-likemetal structure I I1 having the interior formed as two cylindricalcompartments H8, 'II Q, in close proximity but with an intervening wall.Such a "structure may be closed at the upper end by a fiat cover plateI20 bored in the required positions to permit protrusion of the stem I'2I of the solenoid core I22, the ram I23, the needle valve-I 24, and the:piston I 25. The solenoid F26, comprising the coil I2"! and an outerenclosure I28 of magnetic material with a brass, fibre or like tubularinner lining I29, is positioned in the compartment IIB, of the structureupon thebase thereof, with the core I22 when inopez-ative, resting uponthe lower end, and having the stem I 2 passing through a clearance holein the upper disc I30 of the enclosure of the solenoid and extendingthrough the cover plate I-20. in the compartment II9 of the structurethere is received a U-shaped fitting l3I having aciroular "base I32. Onelimb I85 of the fitting l 3-i is bored to serve as the rain bore I34,and the other limb I35 bored to serve as the piston cylinder I36. Thetwo 'bores conveniently communicate by a vtransverse passage I3! in thebase I32-,- and the needle valve I24 is adjustably mounted in anintermediate bore L38; so provided that the cone of the needlemay,according bathe-adjustment oi the-stem or the valve. close tea greateror lesser extent such communication. The :base 1-32 of the fittingis-secured, as by means of screws, to the bottom of the compartment II9. 'I he wall-of the ram =bore I34 is -perforated with one or moretransverse openings I39, and the compartment is flooded with oil orother selected liquid M0,, to 'a. level such that the fitting I-3I isentirely immersed. The piston I extends through a flexible packing ringI4I mounted in the covver .plate I20, and is adapted to receive acrosshead I42, which supports a tubular chuck carrier Hi3 disposedparallel with the vpiston and slidaiblyfitted in bearing bores in spacedbearing lugs 144 formedupon the wall of the structure H I. The carrierI43 is advantageously lined with bushes or an inner tube I45 ofinsulating material having a; massive peripheral flange I46 at the lowerend to bear upon the end of the carrier. A rod of copper :or a likeconductor I4! is received in the inner tube, and has its lowerprotruding end screw-threaded :to engage screw-threads in the tube I45and in the bore of the chuck I48. Above the crosshead the inner tube maybe socured by 'a not 1M9, while the rod may extend into an insulatingenclosure I50 to engage a conducting socket I 5' I for the supply cableI52, which socket may screw upon or be otherwise engaged with the rod I41;

The spring I53, for eitecti ng the return of the stud to th'e' pla'teiscohvn-iehtly coiled about the carrier I 43, between the supportingcups or discs F54, the lower ofwhich isconstrainedin position by aspring ring or collar I55, secured upon the carrier at such a distancefrom the lower bearing lu'gIM as to permit the required travel of thecarrier, while the upper disc may bear against the upper bearing lug I44. r

The movement of the solenoid core is conveniently transmitted to the ramby a lever I 56, that is mounted with the fulcrum pin I51 in a fork-likebearing I58, formed or fitted in the bot-'- tom of an auXi'liar-y coverplate or hood I 59, that is adapted to 'be fitted upon the cover plateI20. Such hood may carry an adjusting screw I60,

adapted to determine the extent of travel of the lever I -56 ,01 of thesolenoid core I22. "The spring I'IiI, for assisting the return of theramI23, may be positioned between the upper end of the correspondinglimb-of the fitting F31, and a collar or spring ring 162 carriedby theram. In'anyconstruction-of the apparatus according'to the "invention, itwill be appreciated that the chuck may be readily oiiset from the axisof movement of the carrier merely by suitable and correspondingformationpf the carrier or by the provision of a supplementary laterallyprojecting carrier. Such an arrangement-permits the weld ing-o'f studsor the likeof unlimited length, if the chuck is of -a-design that allowsthe stud or the like to project from the upper side of the chuck.Provision may be made in any construction of the apparatus for theadjustment of the strength of thespring returning the piston assemblyafter the liftof the stud or the like.

-1. "Electric arc stud welding apparatus, for weldingobjects in theiorin of studs, rivets, tubes and the like tow-the surfaces of plates,bodies and likdma'sses, comprising a body" adapted for support :m anoperative position over thesurface to 'Wihichan object is to be weldedand having there'- in a cylinneriand borespaced apart, a. piston movablein the cylinden-a chuck for the-object movable by and with the-'ipistoma ram movable in the bore, a passage connecting the spacesat the innerends of the said bore and the said cylinder, a fluid medium filling thepassage, the bore and the cylinder between the ram and the piston,operating means for moving the ram in the said bore, and means tendingto move the piston in the direction to expel the fluid medium from thecylinder.

2. Electric arc studwelding apparatus according to claim 1, comprisingalso a storage chamber for the fluid medium, and a passage in the bodyconnecting the storage chamber with the bore at a position immediatelyin advance of the ram when the latter is in the limiting outer positionin the bore.

3. Electric arc stud welding apparatus according to claim 1, having thecylinder and the bore formed in a fitting disposed within a sump in thebody, the sump being charged with fluid for the immersion of thefitting.

4. Electric arc stud welding apparatus according to claim 1, having aregulating valve mounted in the body and adapted to control the rate offlow of the fiuid medium through the passage between the cylinder andthe bore.

5. Electric arc stud welding apparatus according to claim 1, having thecylinder and the bore formed in a fitting disposed within a sump in thebody, the sump being charged with fluid for the immersion of thefitting, and a regulating valve mounted in the fitting for the controlof the cross-sectional area of the passage between the cylinder and thebore.

6. Electric arc stud welding apparatus comprising a body, supportingmeans upon the said body to maintain it in determined disposition uponthe surface to which a stud is to be welded, a cylinder and a bore inparallel relation in the said body, a passage extending between thelower end of the cylinder and the lower end of the bore, a piston in thesaid cylinder, a stud chuck in fixed relation to the piston andpositioned below the body, a spring acting upon the assembly comprisedby the piston and stud chuck to move the piston in the direction of thelower end of the cylinder, a ram in the said bore, a solenoid coilsurrounding the upper part of the bore, a solenoid armature in fixedrelation to the upper end of the ram, and a handle member applied to thesaid body.

7. Electric arc stud welding apparatus according to claim 6, having across-head positioned at the upper end of the piston, a carrier for thestud chuck and guide rods connecting the crosshead with the chuckcarrier.

8. Electric arc stud welding apparatus according to claim 6, comprisingalso a storage chamber of variable capacity provided in the said body,and a passage within the body extending between the said storage chamberand the bore at a position beneath the ram when the ram is in theextreme outward position in the bore.

9. Electric arc stud welding apparatus according to claim 6, comprisinga regulating valve adjustably mounted in the body in a position todetermine by adjustment the cross-sectional area of the passageextending between the cylinder and the bore.

10. Electric arc stud welding apparatus according to claim 6, comprisingalso a storage chamber of variable capacity provided in the said body, apassage extending between the said storage chamber and the bore at aposition beneath the ram when the latter is in its outermost position,and a regulating valve positioned in the body and serving by adjustmentto determine the cross- 10 sectional area. of the passage communicatingbetween the cylinder and the bore.

11. Electric arc stud welding apparatus according to claim 6, comprisingalso a storage chamber of variable capacity provided in the said body, apassage extending between the said storage chamber and the bore at aposition beneath the ram when the latter is in its outermost position,and a regulating valve positioned in the body and serving by adjustmentto determine the cross-sectional area of the passage communicatingbetween the cylinder and the bore, the storage chamber being in the formof a bellows closed at the two ends but communicating at one end withthe passage.

12. Electric arc stud welding apparatus according to claim 6, comprisingalso a storage chamber of variable capacity provided in the said body, apassage extending between the said storage chamber and the bore at aposition beneath the ram when the latter is'in its outermost position,and a regulating valve positioned in the body and serving by adjustmentto determine the cross-sectional area of the passage communicatingbetween the cylinder and the bore, the storage chamber comprising acylinder, a piston in the said cylinder and a spring acting upon thesaid piston.

13. Electric arc stud welding apparatus comprising a body, a cylinderand a bore in axial disposition in the said body, a passage extendingbetween the lower end of the bore and the lower end of the cylinder, apiston in the cylinder, a stud chuck carrier in fixed relation to thepiston and disposed beneath the body, a ram slidable in the bore andextending outwardly therefrom, a solenoid coil within the body andsurrounding the outer part of the bore, an armature in fixed relation tothe ram, a handle member applied to the body, a fluid filling thepassage, the bore and the cylinder beneath the piston and beneath theram, and a spring acting upon the piston assembly in the direction tomove the stud chuck carrier outwardly, and supporting means upon thebody for the support of the apparatus upon the surface upon which thestuds are required to be welded.

14. Electric arc stud welding apparatus according to claim 13, having anannular storage chamber of variable capacity surrounding the ram boreintermediate the cylinder and the solenoid coil, the said storagechamber communicating with the bore at a position beneath the ram whenthe ram is at its outermost limit of travel.

15. Electric arc stud welding apparatus according to claim 13, having anannular storage chamber of variable capacity surrounding the ram boreintermediate the cylinder and the solenoid coil, the said storagechamber communicating with the bore at a position beneath the ram whenthe ram is at its outermost limit of travel, and a regulating valvemounted in the said body for determining the cross-sectional area of thepassage extending between the bore and the cylinder.

16. Electric arc stud welding apparatus comprising a body, separatedcompartments in the said body, a solenoid in one of the saidcompartments, a core axially disposed in relation to and movable in thecoil of the said solenoid, a stem upon the said core projecting alwaysfrom the said coil, a fitting in the second compartment of the body,comprising, in parallel relation, two cylinders communicating at thelower ends within the said fitting, a ram slidably mounted in one thes'aiiii cylinders, a; slidajhly mounted in the second of the safe?cylinders, iierforaltions in tlie first cylinder lieneath the ram whenthe latter is the" outermost position, a motiontiansmitting m'einherdisposes between the ram and the stein of the solenoid core, a:crossfire-ad fixeii' relation to the upper part of the piston, a; guidemember parallel" Withthe piston and also in fixect relation to the c1ossi-liea'd,a carrier'supported by the guide member; a stud chu'ck uponthe said carrier, a spring acting upon the piston and chuck assembly tomove the chuck. outwardly; and a fluidthe second compartment floodingthe said fitting,

1'7. Electric arc stud weldingapparatus according to claim 1 6, in whicha; regulating valve is mounted the said fitting intermediate the twocylinders and determines the cross-sectional area for communicationbetween the two cylinmedium filling the free spaces at the inner ends ofthe chambers and; the communicating" passage, operating means formoving: the second element against the resistance 01. the means actingupon the first element and a stud chuck in fixed relation. with thefirst element,

19 Electric are stud welding apparatus according to claim I8, having astorage chamber of variable capacity commimicasting with thefluidfilled? space: in the second chamber adjacent the inner end of thesecond element when the latter is in its outermost position.

ARTHUR RATCLIFFE AINSWORTH.

REFERENCES CITED UNITED STATES PATENTS Name Date Steele et al. Jan. 20,1925 Number

